What is it about?

Increasing demand for renewable energy has led to a massive expansion of the small-scale hydropower plants and particularly those of run-of-river type. Meanwhile, the awareness concerning river conservation and restoration is being continually increasing. This study focuses on the assessment of environmental flows releases and energy production considering eight hydrological based environmental flows methods. The main goal of this study is to propose a practical approach that allows for quick estimation of the environmental flows releases and alteration due to water diversion for energy production, in the case of run-of-river hydropower plants. For this purpose, the indicators of hydrological alteration approach was applied to characterise flow alteration, and three economic metrics were used to assess the impact on energy production. Downstream Diversion Index was proposed to characterise the degree of water diversion due to energy production. Also, five new simplified indexes derived from indicators of hydrologic alteration approach were proposed to simplify flow alteration characterisation. The results of this study showed that a minor reduction of energy production could significantly improve environmental flows releases for the riverine ecosystem needs. Particularly, proportional dynamic approaches maximise energy production and imposes relatively less flow alteration. Also, it was concluded that following flow parameters: frequency, timing, duration and rates, can be maintained close to the natural regime without necessarily reducing the energy production by choosing the right environmental flows method.

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Why is it important?

Finally, the methodology developed in this study can be a useful decision-making tool to help water managers, by including other relevant information also (i.e., biological, water supply, irrigation, and social) to choose the most appropriate method for the environmental flows determination in the case of run-of-river hydropower plants.

Perspectives

Eight environmental flow methods were applied to estimate the implication on e-flow release and energy production. Downstream Diversion Index (DDI) was introduced to characterise the degree of water diversion. Five new indexes were derived from Indicators of Hydrological Alteration (IHA) to simplify flow alteration characterisation. Proportional dynamic approach preserves essential flow regime parameters and maximises profitability. Hydropower licensing should guarantee adequate e-flow release and ensure feasible investment.

PhD Alban Kuriqi
Universidade de Lisboa

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This page is a summary of: Influence of hydrologically based environmental flow methods on flow alteration and energy production in a run-of-river hydropower plant, Journal of Cleaner Production, September 2019, Elsevier, DOI: 10.1016/j.jclepro.2019.05.358.
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